Craig Stadler climbed into second place at 8-under-par 136 after a second- round, 5-under 67. Jerry Pate is one stroke further back at minus-7. NBC announcer Bob Murphy stands alone in fourth place after his second straight 3-under 69.
Hale Irwin, the 2004 champion, shot 69 and shares fifth place with Allen Doyle and Peter Jacobsen at 5-under-par 139.
Haas opened with a birdie on the first to move three clear of the field at The Westin Savannah Harbor Resort and Spa. However, the hard-charging Murphy made things interesting.
Murphy birdied one and two, but bogeyed three and four. He came right back to convert birdies on five and six to get to minus-5. Murphy birdied the eighth to join Haas, who bogeyed No. 6, in the lead at minus-6. Murphy would remain there for a while with five pars in a row.
Haas parred the final three holes of the opening nine, before catching fire around the turn. The 52-year-old drained back-to-back birdies from the 10th to get to 8 under. Haas two-putted for birdie on the par-5 13th.
The two-time winner on the Champions Tour made it two straight as he also birdied No. 14. After a pair of pars, Haas climbed to minus-11 with a 6-foot birdie putt on the 17th. However, he faltered to a bogey at the last.
Stadler posted bookend birdies on the front nine at one and nine to make the turn at 5 under. He carded birdies on 11 and 13 to take second place. Stadler notched his final birdie on the 16th to end two behind Haas.
Murphy did get to minus-7 with a birdie at the par-4 14th, but gave that shot back as he bogeyed the 16th.
Tom Jenkins (69) and Mark Johnson (70) share eighth place at 4-under-par 140. John Jacobs and Loren Roberts each posted 3-under 69s to move to minus-3. They were joined in 10th place by Dave Eichelberger (70), Tom Wargo (73) and Larry Nelson (70).
Defending champion Des Smyth struggled to a 1-over 73 Saturday with three bogeys and two birdies. He tumbled into a tie for 17th at 1-under-par 143.